Abstract
The effect of the lipidic environment on the emission properties of chlorophyll a in mixed Langmuir-Blodgett films was studied. For a pigment:lipid molar ratio of 1:100, the fluorescence excitation and emission spectra have maxima at 438 nm and 678 nm respectively. Two lifetimes were necessary to fit the time-resolved fluorescence decay curves: 4.6 ns and 2.2 ns with respective contributions of 74% and 26%. The long component is attributed to the monomeric pigment and the short component to hydrated dimers or oligomers. Lecithins and galactolipids have identical effects on the emission properties of chlorophyll a, indicating that there is no specificity in the pigment-lipid interactions. However, some lipids are found to have the same effect as acids on the chlorophyll monoayers and, among them, some require careful purification in order to eliminate this acidic reaction. Those data suggest that the lipids of thylakoid membranes are good diluents and are not destructive to chlorophyll a.
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